1. Field of the Invention
This invention relates to an optical data recording and reproducing method. More specifically, this invention relates to an optical disk recording and reproducing method which makes possible to record data encoded by different encoding circuit at different data compression rate and to reproduce the data.
2. Description of the prior Art
Initialized by the vast increase in information that needs to be processed, optical data storage system having become very important system particularly because of their high storage density per area. Most of the recent optical information storage systems rotating single optical disk are used on which the information is digitally stored in concentric circular tracks in an ordered, predefined manner to allow chronological fast reading and fast random access to desired pits of data.
In order to accomplish even more storage capacity of optical disk systems for enormous information processing, such as video or picture communication like so called video-on-demand service, multiple disk systems have been proposed. An optical disk system equipped with two or more data layers may in theory be accessed as different disks by changing the focal point with moving lens. Example of this type of state-of-the-art include U.S. Pat. No. 5,202,875 issued Apr. 13, 1993 to Rosen et al.; Japanese Published Application, 63-276732 published Nov. 15, 1988 by Watanabe, et al.
Such a multiple disk recording and reading system is applied to varied optical disk information storage systems. For example, a digital video disk (DVD) system for home entertaining is one of the typical application. The mentioned advantage of vast storage capacity may contribute especially for video signal transmission. In order to record the video data efficiently onto the optical disk, a video data compression technique is one of the key technologies. A standardized video data compression rate has been proposed, which is called MPEG (Moving Picture Experts Group). However, for the home entertaining purposes, a more flexible function is required. The ability to record data at different data compression rates and to reproduce the recorded data, must be provided.
The present invention has for its object to provide a multi-layered optical disk recording and reproducing system which is able to record data encoded by different encoding circuits at different data compression rates and to reproduce the data by a selected decoding circuit.
The object of the present invention can be achieved by an optical data recording and reproducing method, the recording method comprising the steps of: loading a multi-layered optical disk which has M data layers (wherein M is an integer greater than 1), receiving an operator""s signal to record data on an Nth data layer of the multi-layered optical disk at a certain data compression rate (wherein N is an integer greater than 1 and not greater than M), operating a routing circuit to transmit the data to a determined encoding circuit in order to compress the data at a predetermined data compression rate, recording the data on predetermined position at the predetermined data compression rate, and rewriting table of contents (TOC) data to record data about the data compression rate of the newly recorded data.
And the object of the present invention also can be achieved by an optical data recording and reproducing method, the reproducing method comprising the steps of: loading a multi-layered optical disk, which has M data layers (wherein M is an integer greater than 1), reproducing a table of contents (TOC) data recorded in the multi-layered optical disk, storing the reproduced TOC data in a memory, receiving an operator""s signal to reproduce selected data stored in the multi-layered optical disk, referring to the TOC data stored in the memory to identify the data compression rate of the selected data, and operating a routing circuit to transmit a readout signal of the selected data to the determined encoding circuit in order to decompress the selected data.
For a fuller understanding of the nature and advantages of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.